光电子学
石墨烯
材料科学
异质结
逐层
图层(电子)
纳米技术
作者
Xiaoqing Chen,Xiaolong Liu,Bing Wu,Haiyan Nan,Hui Guo,Zhenhua Ni,Fengqiu Wang,Xiaomu Wang,Yi Shi,Xinran Wang
出处
期刊:Nano Letters
[American Chemical Society]
日期:2017-09-14
卷期号:17 (10): 6391-6396
被引量:96
标识
DOI:10.1021/acs.nanolett.7b03263
摘要
Interfacing light-sensitive semiconductors with graphene can afford high-gain phototransistors by the multiplication effect of carriers in the semiconductor layer. So far, most devices consist of one semiconductor light-absorbing layer, where the lack of internal built-in field can strongly reduce the quantum efficiency and bandwidth. Here, we demonstrate a much improved graphene phototransistor performances using an epitaxial organic heterostructure composed of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and pentacene as the light-absorbing layer. Compared with single light-absorbing material, the responsivity and response time can be simultaneously improved by 1 and 2 orders of magnitude over a broad band of 400-700 nm, under otherwise the same experimental conditions. As a result, the external quantum efficiency increases by over 800 times. Furthermore, the response time of the heterostructured phototransistor is highly gate-tunable down to sub-30 μs, which is among the fastest in the sensitized graphene phototransistors interfacing with electrically passive light-absorbing semiconductors. We show that the improvement is dominated by the efficient electron-hole pair dissociation due to interfacial built-in field rather than bulk absorption. The structure demonstrated here can be extended to many other organic and inorganic semiconductors, which opens new possibilities for high-performance graphene-based optoelectronics.
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